1. Field of the Invention
The present invention relates in general to a liquid crystal display LCD module driving apparatus, and more particularly to an LCD module driving apparatus with one driving circuit in which LCD driving data output ports of an LCD driving controller are used for outputting LCD driving data at a timing for driving a group of scanning electrodes and also a part of the LCD driving data output ports are used once more for outputting the LCD driving data at another timing for driving another group of scanning electrodes of the LCD panel, thereby causing only one driving circuit to be equipped, thus simplifying the construction thereof.
2. Description of The Prior Art
With reference to FIG. 1, known LCD panels, each having twenty character display parts sequentially arranged in a line, generally have a plurality of pixel electrodes and a common electrode which are disposed between an upper substrate 11 and a lower substrate 12. Here, each pixel electrode corresponds to each and every dot and is provided with a color filter. In manufacturing such an LCD panel, the upper and lower substrates 11 and 12 receive therebetween a liquid crystal which is injected between the pixel electrodes and the common electrode, then are hermetically sealed, thereby providing a character display member 11a disposed on the upper panel 11. Here, the upper and lower substrates 11 and 12 are generally made of glass, while the pixel electrodes and the common electrode are generally formed as coating a transparent conductive coat such as an ITO (Indium Tin Oxide) coat.
As shown in FIG. 2, the character display member 11a of the conventional LCD module is comprised such that one character display consists of 5.times.7 dots, one character display cursor consists of 5.times.1 dots. Therefore one character display part consists of 5.times.8 dots, resulting from adding the one character display of 5.times.7 dots to the one character display cursor of 5.times.1 dots. Thus upon sequentially arranging twenty character display parts, each consisting of 5.times.8 dots, in a line, the character display member 11a results.
On the other hand, the known LCD panel is provided with a scanning electrode pattern of C1 to C8 which are applied with scanning signals, furthermore, provided with a signal electrode pattern of S1 to S100 which are applied with character display data, as shown in FIG. 3. Thus, upon being applied with the scanning signals and the character display signals, each pixel electrode for each dot disposed at a cross position of each signal electrode and each scanning electrode may be driven by means of a thin film transistor.
As shown in FIG. 4, the known apparatus for driving such a LCD module having the character di splay member 11a consisting of twenty character display parts sequentially arranged in a line, hereinafter said type of LCD module being referred to simply as "the LCD module", includes a LCD driving controller 20 which outputs scanning signals from scanning signal output ports Q1 to Q8 to the scanning electrodes C1 to C8 of the LCD panel 10 synchronously with generation of LCD driving data corresponding to the one hundred dots which corresponds to the twenty character display parts. At this time, the LCD driving controller 20 directly outputs a part of the LCD driving data from the driving data output ports D1 to D40 thereof to the signal electrodes S1 to S40 of the LCD panel 10, but indirectly outputs the other LCD driving data, which overflows the driving data output ports D1 to D40 thereof, to the signal electrodes S41 to S100 by way of a pair of driving circuits, that is, a first circuit 30 and a second circuit 40.
Here, the first driving circuit 30 receives the other LCD driving data, which overflowed the driving data output ports D1 to D40 thus applied from the ports D1 to D40 thereto, then outputs a part of the received LCD driving data from output ports Y1 to Y40 thereof to the signal electrodes S41 to S80 of the LCD panel 10, while the second driving circuit 40 receives the LCD driving data, which overflowed the output ports Y1 to Y40 of the first circuit 30 thus applied from the ports Y1 to Y40 thereto, then outputs the received LCD driving data to the signal electrodes S81 to S100 of the LCD panel 10.
The operation of the known apparatus for driving the LCD module having the above construction will be described hereinafter.
Upon receiving character display data and a control signal outputted from a central processing unit (CPU, not shown) of an external system, the LCD driving controller 20 generates LCD driving data for driving the LCD panel 10 by means of a ROM, which is adapted for generating the character, synchronously with generation of the scanning signals. The scanning signals are sequentially outputted from the scanning output ports Q1 to Q8 to the scanning electrodes C1 to C8 of the LCD panel 10, while the LCD driving data is outputted from the driving data output ports D1 to D40 of the controller 20.
At this time, the first to fortieth signal electrodes S1 to S40 of the LCD panel 10 are directly applied with the LCD driving data directly outputted from the driving data output ports D1 to D40 of the controller 20. However, if the LCD driving data overflows the driving data output ports D1 to D40 of the controller 20, the overflown LCD driving data is outputted from the driving data output ports D1 to D40 in order to be received in the first driving circuit 30, then outputted from the driving data output ports Y1 to Y40 of the first driving circuit 30 to the forty first to eightieth signal electrodes S41 to S80 of the LCD panel 10. In addition, if the LCD driving data also overflows the output ports Y1 to Y40 of the first driving circuit 30, the overflown data is outputted from the first circuit 30 in order to be received in the second driving circuit 40, then outputted from the output ports Y1 to Y20 of the second circuit 40 to the signal electrodes S81 to S100 of the LCD panel 10.
Here, the second circuit 40 generally has forty driving data output ports but uses only twenty output ports in outputting the overflown LCD driving data.
The scanning electrodes of the LCD panel 10 comprise, as described above, eight electrode lines of C1 to C8, thus, the one hundred signal electrodes S1 to S100 of the LCD panel 10 are applied with the LCD driving data at 1/8 duty cycle in one screen driving period of the LCD module in order to drive the LCD pane 10.
In brief, the one hundred signal electrodes S1 to S100 of the LCD panel 10 are applied with the LCD driving data in order to drive the character display member 11a under such manner that the first to fortieth signal electrodes S1 to S40 are directly applied with the data directly outputted from the output ports D1 to D40 of the controller 20, and the forty first to eightieth signal electrodes S41 to S80 are applied with the LCD driving data outputted from the first driving circuit 30, additionally, the eighty first to hundredth signal electrodes S81 to S100 are applied with the LCD driving data outputted from the second driving circuit 40. Thus, the known apparatus for driving the LCD module has disadvantage in that it additionally includes the second driving circuit 40 which, despite of being provided with forty output ports due to the conventional chip construction, uses only twenty output ports of the forty output ports in outputting the LCD driving data, thereby deteriorating the using efficiency of the second circuit 40. Furthermore, the known apparatus comprises two driving circuits 30 and 40 for outputting the LCD driving data, thereby causing the construction and the manufacturing process of the apparatus to be complex, thus deteriorating the productivity.